OFDM and OFDMA wireless communication systems under IEEE 802.16 use a network of base stations to communicate with wireless devices (i.e., mobile stations) registered for services in the systems based on the orthogonality of frequencies of multiple subcarriers and can be implemented to achieve a number of technical advantages for wideband wireless communications, such as resistance to multipath fading and interference. Each base station (BS) emits and receives radio frequency (RF) signals that convey data to and from the mobile stations (MS).
Under the current versions of the IEEE 802.16 standard for the OFDMA systems, the MS may be required to report a variety of channel quality information (CQI) back to the BS. For example, the MS may be required to report an effective carrier-to-interference plus noise ratio (CINR) back to the BS. In conventional systems, a MS generates the effective CINR value by utilizing a physical CINR measurement as an index into a mapping table. The effective CINR values of the mapping table are typically calculated in an effort to compensate for expected channel conditions and are typically fixed during manufacture of the MS. The BS receives effective CINR values reported by the MS and selects a coding scheme corresponding to the effective CINR value for encoding and modulating subsequent downlink (DL) data bursts to the MS.
Unfortunately, as channel conditions change, the effective CINR values generated using the fixed mapping table may result in the selection of sub-optimal coding schemes. Despite extensive testing, it is very difficult to optimize a mapping table such that it addresses the variety of field conditions an MS may encounter. Updating a mapping table in an MS is not feasible as, unlike with a BS, there is no simple upgrade method available due to the sheer volume of units.